Continuous strip furnace



Pa[ented June 20, 1939 UNITED STATES PATENT FFICE 9 clailns.

'he invention relates t0 continuous furn2ces for the heating, heat treating, annealing or coat ing of metal strips and more particularly to furnaces in vhich the heating of the strip is produced by electric current passed through the strip An object of the invention is to provide a ur nace 0f this general character in vvhich the strip is continuously passed between two contacts in an electric circuit, one contact being a roller and the 0ther contact being an aqueous bath through Which the strip iS passed before entering the furnace' further object is t0 provide such 3' furnace ln which the roller contac la'y be vvater c00led and adjustable to vary the c00ing 0f the srip( A further object is t0 provide a furnace of this type in which the aque0us bath Inay be ar pickling Solution or the ike nleans being provided be 20 tween the aqueous bath and the furnace for washing and drying the strip before it enter5 the furnace further object of the inprovenent is to pr0- vide means controued by the tenlperature of the Strip for varying the power input to the strip Without interrupting the current An0ther object is t0- provide rons at oppdsite ends of the furnace between Which Water or other Huid is continuously clrculated for purpose 0f 30 recuperation ';'he above 0bjects together vith others which Will be app8rent from the acc0mpanying drawing and the fonowing description, or Which nlay be later referred to' !Tlay be att8ined by construct- 3 ing the mpr0ved furnace in the manner ilustrated in the acconlpanying drawing, in vvhich Figure l is a diagralnnatic 10ngitudinal seci0naI view of an annealing furnace embodying the invention; and

40 Fig 2 is a similar view of a Inetal coating furnace embodying the invention Simnar numeras refer to smilar parts throughout the several ngures of the drawing Referring flrst t0 the construction illustrated 45 in Elg 1 0f the drawing, an e 0ngated hood or tunnel is pr0vided, indicated generally at lu and preferably consructed S0 as to form aL heating chamber ll, an nitial cooling chamber l2 and a flnal c00ing chamber 3 0f considerable length 60 aS compared with the initial co01ing chamber lz. This hood or tunnel may be rovded with any suitab]e and vell kn0vvn lining ()f heat insuating Inaterial and Znay be supported above the n00r by any suitable raneW0rk such as indicated gen- At the e11trance end of the hood or tunnel is 10cated a pair of r0lls indicated at ls and ls, betvveen Which the incon1ing strip, indicated at s, is passed, these rons preferably being honow and provided with nleans for circulating water or other fluid therethr0ugh one or both of these rons nlay be used as contact rons as shown in Fig. 1 in which case a' Switch 34G rnay be provided for connecting either the roll l5 0I` the electrode 32 0r both in the cir cuit 3 l' vvhere either or both of these rolls is to be used for electric contact vvith the strip the dialneter of the T011 Should be at leas... two hundred tiInes the thickness of the srip under treat Inent and Should have a contact etrea. between the Strip and the roll of at least four tinles the cross sectional area of the st rip' It should also be underst00d that where the !'0ll is llsed for contact, both the strip and roll Should be bright and clean and maintained in a non0xidizing atnlosphere. If only the roll is used for contact the strip nlay be cleaned by the pickling ba(th shown or may be 0therwise cleaned before c0ning t0 the furnace sinilar pair of tolls indicated at IT and l. 2;; is located at the discharge end of the tunnel or hood the Strip being passed between the sa,!le before it leaves the furnace 'Ihese rolls 9re also preferably honow and adapted to have a. fluld passed therethrough. For the purpose of recuperation, the two pairs of rolls nlay be connected together by the pipes l9 a nd |I the pipe l, connecting the rolls |G and l'| 9.nd the pipe z| connecting th rolls ls and l8.

The rolls |5 and |6 are connected at one end by a pipe z| and therons |'l and l8 are sim"arly connected by a pipe -22. A pump or the like as indicated at 23 r!9y be located in one of the plpes |9 0r 2@ for causing a continuous circulation of water or other nuid through the rous |5 ls n 4n and Whereby heat absorbed from the strlp by the rons |'l and is returned to the rons |5 and ls t0 assist in the preheating 0f the Strlp At the juncture of the heaing chaniber a.nd inltial cooling chamber ls 0cated a r01 z over 4 Which the strip is passed in its passage through the furnace. l1is r0l nlay be formed of sllltable heat resi...ting al0y and if desired Tnay be hollow and continuously c00led by passing vater OT Oher c00ing nuid therethrough, as by the pipe 2b In Such 1atter Cse he ro! may be of copper or sinilar maerial and of high heat and electrica1 conductive capacity' Ihis r0ll is a' contact roll for passing electric current through the strip and is 10cated in one s id contact roll and 9. rII adjustble elative t0 Said contact T011 for varying the are8 0f the strip contacting Said contact rou whereby the strip is heated by electric Tesistance and then rapidly c00led as it passes through the furn ce.

2 'L continuous strip furnace including an elongated heating chamber, nle ns for l11a'ilta il1- ing 3. non0xidizing atnsphere in the heting chaTnber, an aqueous ba.th COInprising a. pickling S0lution outside of the entrance end of the fur nace, a contact roll vvithin the heatng chamber adjacent t0 the discharge end there0f, an elec trode in the aqueous bath, an electric cicuit connected to said electrode in the aqueous bath and to said contact roll, and nlea...ns for passing a metal Strip through Said aqueous bath but `I0t in contact vvith said electrode and then through the heating chamber and over Sid contact l'011 vvhereby the Strip is heated by resistance as it passes through the furnace 3, A continuous strip furnace including an e10ngated heating chaTnber, nleans for I19intaining a nonoxidizing atlnosphere in the heating chamber, an aqueous bath outside 0f the entrance end of the furnace, 3 Gontact !'0ll vvithin the heating chamber adjacent to the discharge end there0f, means for cooling Said contact roll, an eectr0de within Said aqueous bath, an electric circuit connected to the electrode in said aqueous bath and to said contact T011, 1nd Ineans fol passing a nleta1 strip through said aqueous bath but not in contact vvith said electrode and the1 through the heating ch arnber and over said contact T011 and ITleans for varying the allea 0f the strip contacting said contact ro11 vvhereby the strip is heated by resistance and then rapidly c001ed as it passes through the furnace.

^^L Continuous strip furnace including n e10ngated heating chaInber, Ineans for Ilaintaining a n0n0xidi ing atn10sphere in the heating cha!nber, an aqueous bath outside of the entrance end of the furnace, a contact T011 vithin the heating chaInber adjacent t0 the discharge end thereof, nleans for c001ing said contact T011, an electric circuit connected to said aqueous bath and to said contact T011, and Ineans fo1' passinganletal strip through Said aqueous bath and then thTough the heating chalnber and over Said contact roll Whereby the strip is heated by resistance and then rpidly cooled as it passes through the flll nace, and an adjustable vvater c001ed T01 lovable relative to and coOperaing vvith said contact roll for yarying the area of the strip con tacting said contact roll contr011ing the anlount of c00ling of the Strip.

5. A continuous strip furnace including ,)n elon gated heating chnber, nleans for T19intaining a n0noxidizing atmosphere in said heating chan1- ber an aqueous contact bath c0prising 2 pickle s01ution spaced iron1 the entrance end of the heating chaInber, 9 resista11ce drying sp8ce between the aqueous bath and the he ting chaInber, Washing nleans between the pickle s0lui0n and the drying space, 8 cont ct T011 vvlthin the disch rge end of th heating chnber an electric circuit conected at opposite sides 0 the queous contact bth and the contact T011, and Tleals for pEssing a' Inetal strip through the aqueous contact bth, WEshing nleans, drying space a.1d` heating chalnber nd over salid cont ct T011.

6, A continuolis strip fuTnce including an elongated heating chan1ber, nleans for la'intaini1g 'a' non0xidizing atnosphere il1 Said heating chan1- ber 'an aqueous contact bath c0!prising a pickle solution spaced from the entrance end of the heating chamber, Tesistance drying space be tvveen the aqueous ba'th and the heating chalnber, a }vashing batt1betwee1 the aqueous b th and the drying space, 9' c0ntct T011 vvithin the discharge end of the heating chan1ber, an electric circuit connected at opposite sides to the que0us contact bath and the contact T011, and means for passing al met l strip through the aqueous contact batl1, vva'shilg b8lth, drying sp8ce and heating chanlber nd over said contact roll.

7. A continuous strip furnace 1!1cl[1ding an elongated heating chan1ber, an electtic conta.ct llear the entTnce end of the chanbe1', !1 elec tric contact T011 at the dschalrge end of the chatnber, a fluid cooled roll sp ced fron1 the con contact rol1, an adjustable l'0ll spaced !'0n1the fluid cooled T011, a electric circuit connected to said electric cont3.ct and to s8id cont8ct T011, n1eans for passing s. nletal strip through the furnace in cont9ct with said elctTic cont ct and 'Said contact T011 snd 1Tlea ns for l10ving salid adjuStble T011 fol v rying the ae9 0f the stip contacting Said cooled roll for controlling the amount of c001ing of the strp continuous strip furn8ce including En e10ngated heating ch1ber, an electric contact near the entrance end of the cha!nber. an eec tric conta.ct roll at the discharge end of the cha.n1be1', 8 fluid c00led roll sp8ced 0 the contact roll, an aldj1stauble cnoled T011 spaced fron the fluid c001ed roll, an electric cir cu t connected t0 Said electric contact and to said cont ct T011, InenS fol' passing a. Inetl Strip through the furnace in cont ct with said elec tric contact and s id contact T011, 8nd nlegns f0; nloving salid 3djustable roll for varying the area of the`strip contacting said 000led T01ls for controlling the amount of coollng of the strip.

9. A continuous strip furnace includng an elongated heating chalnber an electric contac near the entr8nce end of the ch n1ber n electri() contact fluid cooled T011 .t the d1schBrge end of the chanber, 9 1uid c00led T011 Spced fron1 tlle contact roll, an adjustable ron sp ced fron1 the fluid c001ed roll, an e1ectric ccllit connected to sgid electric cont8ct and to said cont8ct oll, n1ens for passing a' 'Ie81 strlp through the furnace in contact wth said electric contact and said contaict' oll, and nle ns for Inoving said adjustable 011 f0l' vgryi1g the B1ea o the Strlp contacting s id rols f01 cont!0lling the anlount of c001ing of the strip.

TEADDEUS E. BAIl. 

